During well testing operations, hydrocarbons flow at surface for a short period of time. Most of the well tests occur during exploration, appraisal, and initial completion of a well. As of today, the easiest way to dispose of unwanted hydrocarbons is to burn them. Oil and gas may be separated upstream of the burners/flares to allow an effective combustion.
Different types of separators exist on the market. One of the specificities of well testing operations is that they arise at the early stage of the life of a well. After drilling operations, reservoirs are contaminated with brines and other drilling fluids. Well testing separators may thus be able to handle multiphase flow of water, oil, and gas. Vertical separators have been used in the art as well as horizontal gravitational separators. Horizontal gravitational separators are believed to have better capabilities than vertical separators with regard to multiphase separation. The increasing demand, however, for enhanced rate gas/liquid separators presents diverse challenges.
The main constraint in designing a gas/liquid separator arises in the size and weight limits dictated by transportation authorities. By restricting the size of the separator vessel, gravitational capacities decrease, flow rate capacities decrease, and expected volumes decrease as well. To counteract this constraint, particular care may be given to the design of internal devices.
Internal devices, such as demisters can be made of a single demister element, which allows liquid components in natural gas to be captured, and the gas to pass through. However, increasing flow rates can decrease the efficiency of the single element demister. Demisters can also employ a second element to serve the same function after the gas passes through the first demister element. Mist extractors of this type may be seen in U.S. Pat. No. 4,539,023, where a ceramic mist extractor and a stainless steel mist extractor are described. The gas stream is forced to flow through a settling section where turbulence ends. In the settling section, the heavier liquids drop out and then the gas stream passes over a secondary tall baffle down through the primary ceramic mist extractor and ceramic chips or bodies therein and then upwardly over a tall baffle which forms a partition across the interior of the tank except an upper most portion thereof. The gas stream then flows downwardly through the stainless steel mist extractor. The ceramic mist extractor and the stainless steel mist extractor are horizontally oriented and segregated from each other in a formation that causes the gas stream to change direction in order to flow through the next element. The restricted gas flow through the mist extractors results in a pressure drop across the extractor material and causes them to operate at a lower temperature than that of the gas stream.
External devices such as sight glasses may be attached to separators in order to give visual confirmation of gas and liquid levels within the separator. Coriolis meters have been added to outlet pipes attached to separators in order to determine mass flow rates and densities of moving streams of gas and oil extracted by the separator in an attempt to determine the contents of the gas and oil extracted by the separator. However, Coriolis meters may have difficulty providing accurate mass flow rates and densities of gasses entrained with liquid. Further, it may be difficult to determine the content of the gasses separated by the separator and output through the Coriolis meter without further testing of gas samples.